Thermal insulation structure for heating device

ABSTRACT

A thermal insulation structure is disposed at an exterior of a chamber of a heating device. The thermal insulation structure includes a heat conduction layer, a heat storage layer and a reflection layer. The heat conduction layer is adapted to conduct heat from the chamber to the heat storage layer. The heat storage layer is adapted to store heat. The reflection layer is adapted to reflect radiation heat back to the chamber, whereby a temperature of the chamber could be kept at a constant so as to reduce heat dissipation of the chamber.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention is related to insulation of a heating device, andmore particularly to a multi-layered thermal insulation structure.

2. Description of Related Art

Conventional heating devices include a chamber which is assembled with aheat source therein. However, heat generated by the heat source would bedissipated to the outside due to heat conduction from wall surface ofthe chamber, which makes heat dissipation difficult to be avoided. If auser accidentally touches an exterior surface of the chamber, it ispossible that the user might get burned. In order to reduce heatdissipation, an improved heating device which further includes a housingdisposed outside of the chamber is provided. A gap is provided betweenthe housing and the chamber to isolate heat conducted from the chamberso as to lower a temperature on the exterior surface of the chamber.

However, in addition to heat conduction, the heat transferring path alsoincludes heat convection and heat radiation. Even if the aforementionedheating device could isolate heat conduction dissipated from thechamber, it is possible that the heat of the chamber would betransferred to the outside through heat convection and heat radiation.Hence, heat dissipation cannot effectively be eliminated for theconventional heating devices and there is still a need to provide animprovement on reducing heat dissipation of a heating device.

BRIEF SUMMARY OF THE INVENTION

In view of the above, an object of the present invention is to provide athermal insulation structure which could reduce heat dissipation fromthe chamber effectively.

The present invention provides a thermal insulation structure for aheating device. The thermal insulation structure is disposed at anexterior of a chamber of the heating device, which is disposed with aheat source therein. The thermal insulation structure includes a heatconduction layer, a heat storage layer and a reflection layer, whereinthe heat conduction layer disposed on the exterior of the chamber; theheat storage layer is disposed on the heat conduction layer and contactsthe heat conduction layer; the heat conduction layer is adapted toconduct heat from the chamber to the heat storage layer; the reflectionlayer is disposed on the heat storage layer and includes a heatreflection surface which faces the heat storage layer.

An advantage of the present invention is that the heat conduction fromthe chamber could be absorbed by the heat conduction layer and storedinto the heat storage layer to maintain the temperature of the chamber.In addition, the reflection layer could reflect radiation heat back tothe heat storage layer and the chamber so as to reduce heat dissipation.

The thermal insulation structure could be applied to heating devicessuch as an oven, a baking apparatus, a heating apparatus, a thermalinsulation apparatus, etc. The heat source could be an electrothermicheater, a burner, or an object or food to be kept at a constanttemperature.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present invention will be best understood by referring to thefollowing detailed description of some illustrative embodiments inconjunction with the accompanying drawings, in which

FIG. 1 is a perspective view of a kiln of a first embodiment accordingto the present invention;

FIG. 2 is an exploded view of the kiln of the first embodiment;

FIG. 3 is a perspective view of the door of the first embodiment;

FIG. 4 is a perspective view of the cavity of the first embodiment;

FIG. 5 is a cross-sectional view of the kiln of the first embodiment;

FIG. 6 is a schematic view of the thermal insulation structure of thefirst embodiment;

FIG. 7 is a partial cross-sectional view of the kiln of first theembodiment;

FIG. 8 is a perspective view of the combustion device of the firstembodiment;

FIG. 9 is an exploded view of the combustion device of the firstembodiment;

FIG. 10 is a schematic view showing that inside of the cavity of thekiln as illustrated in FIG. 1 is being heated;

FIG. 11 is a perspective view of a combustion device of a secondembodiment according to the present invention;

FIG. 12 is a partial perspective view of the combustion device of thesecond embodiment;

FIG. 13 is a perspective view of a kiln of a third embodiment accordingto the present invention, wherein a thermal insulation structure and aheat conductive structure are omitted;

FIG. 14 is a cross-sectional view of the kiln of the third embodiment;

FIG. 15 is a schematic view of a kiln of a fourth embodiment; and

FIG. 16 is a schematic view of a kiln of a fifth embodiment according tothe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following illustrative embodiments and drawings are provided toillustrate the inventive subject matter, its advantages and effects sothat it can be clearly understood by persons skilled in the art afterreading the disclosure of this specification.

As illustrated in FIG. 1 to FIG. 10, a kiln 100 of a first embodimentaccording to the present invention includes a stove 10, a housing 36, adoor 38, and a heat source which is a combustion device 40 as anexample.

The stove 10 includes a cavity 12 and an entry 14. Wherein, the cavity12 includes a front section 122 and a rear section 124. The frontsection 122 communicates with the entry 14, and a top wall surface atthe front section 122 tilts toward the entry 14 downwardly. The rearsection 124 is away from the entry 14. An inner wall surface 124 a islocated at the rear section 124 and faces the entry 14. A top wallsurface at the rear section 124 tilts upwardly in a direction away fromthe inner wall surface 124 a. The cavity 12 further includes a middlesection 126 which is located between the front section 122 and the rearsection 124. A top wall surface at the middle section 126 is higher thanthose of the front section 122 and the rear section 124, wherein amaximum distance L between the top wall surface and a bottom of themiddle section 126 along a direction from the front section 122 to therear section 124 remains the same (as shown in FIG. 5). That is, themaximum distance L between the between the top wall surface and thebottom of the middle section 126 remains as a constant in the middlesection. The top wall surface at the rear section 124 tilts downwardlyfrom the middle section toward a direction away from the entry 14.

In the current embodiment, the stove 10 includes a chamber 16, an airguide structure 18, a heat storage member 22, a thermal insulationmember 24, and a base 28. Wherein, the chamber 16 is a substantiallyarch shape and made of metal such as stainless steel. A front end of thechamber 16 is open, and the entry 14 is formed at the front end of thechamber 16. A rear end of the chamber 16 is closed, and includes theinner wall surface 124 a. The cavity 12 is within the chamber 16. Thechamber 16 is disposed on the base 28, wherein the chamber 16 includes amain body 162, a first inclined plate 164 and a second inclined plate166. A middle part 162 a is formed on a top of the main body 162,wherein the first inclined plate 164 and the second inclined plate 166are joined to a front end and a rear end of the middle part 162 arespectively. The first inclined plate 164 is corresponding to the frontsection 122 of the cavity 12, the middle part 162 a is corresponding tothe middle section 126 of the cavity 12, and the second inclined plate166 is corresponding to the rear section 124 of the cavity 12. An innersurface of the first inclined surface 164 constitutes the top wallsurface of the front section 122, while an inner surface of the secondinclined plate 166 constitutes the top wall surface of the rear section124.

An air outlet 164 a is formed on the first inclined plate 164 of thechamber 16, wherein the air outlet 164 a communicates with the entry 14and is disposed between the top of the front section 122 of the cavityand the entry 14. The air guide structure 18 is disposed in the chamberand located at the top of the front section 122 of the cavity 12,wherein the air guide structure 18 communicates with the air outlet 164a. In the current embodiment, the air guide structure 18 includes aguide plate 182 and a lid plate 184. The guide plate 182 is joined tothe first inclined plate 164, wherein an angle between the guide plate182 and the first inclined plate 164 is smaller than 90 degrees. The lidplate 184 is an arch shape, wherein two sides of the lid plate 184 arejoined to the chamber 16, and an inner surface of the lid plate 184 isjoined to a peripheral edge of the guide plate 182. A space S1 isenclosed by the lid plate 184, the guide plate 182, and the firstinclined plate 164. The space Si is adapted to receive the heat storagemember 22. An exhaust pipe 20 is joined to the lid plate 184 anddisposed above the air guide structure 18. The guide plate 182 tiltsupwardly from the air outlet 164 a toward a direction away from theentry 14. Whereby, an exhaust channel E is formed by the guide plate 182of the air guide structure 19 and the exhaust pipe 20. The heat storagemember 22 covers the first inclined plate 164, i.e., the heat storagemember 22 is disposed at an exterior of the chamber 16 at the top of thefront section 122 of the cavity 12, and at least part of the heatstorage member 22 is located in the space S1 and contacts the air guidestructure 18. In the current embodiment, part of the heat storage member22 is located in the space S1, while another part of the heat storagemember 22 protrudes out of the space S1, and the air guide structure 19contacts an exterior surface of the guide plate 182. Preferably, athermal conductivity of the heat storage member 22 is equal to orgreater than 0.7 W/(mK), and a heat storage density thereof is equal toor greater than 1 KJ/m³K. In the current embodiment, the thermalconductivity of the heat storage member 22 is 0.8˜0.93 W/(mK), and theheat storage density thereof is 1.4 KJ/m³K. The heat storage member 22includes a plurality of stacked particles (e.g. sands, or pebbles), andthe air fills the gaps between the stacked particles. By enclosingwithin the space S1, the particles could be prevented from sliding down.

In addition, the thermal insulation structure 24 covers the exterior ofthe chamber 16 which is corresponding to the rear section 124 and themiddle section 126, and is disposed at an outer peripheral of the heatstorage member 22. A heat insulation effect of the thermal insulationstructure 24 is better than that of the heat storage member 22, wherebya temperature at the middle section 126 of the cavity 12 is higher thanthat of the front section 122 so as to increase heat convection. Inpractice, the heat storage member 22 also could be omitted, and part ofthe thermal insulation structure 24 could extend to a position where theheat storage member 22 locates. As illustrated in FIG. 6, the thermalinsulation structure 24 includes, from outward to inward, a firstreflection layer 241, a barrier layer 242, a thermal insulation layer243, a second reflection layer 244, a heat storage layer 245, and a heatconduction layer 246.

The thermal conductivity of the heat conduction layer 246 is greaterthan that of the heat storage layer 245. The heat conduction layer 246is adapted to absorb part of heat from the chamber 16 rapidly andtransfer the heat to the heat storage layer 245, whereby the heat couldbe stored into the heat storage layer 245. Wherein, the thermalconductivity of the heat conduction layer 246 is equal to or greaterthan four times of that of the heat storage layer 245. Preferably, thethermal conductivity of the heat conduction layer 246 is equal to orgreater than 35 W/(mK), and more preferably, greater than 40 W/(mK). Inthe current embodiment, the thermal conductivity of the heat conductionlayer 246 is between 40.096 and 46.285 W/(mK). Meanwhile, the thermalconductivity of the heat storage layer 245 is preferably equal to orsmaller than 8.5 W/(mK), and more preferably smaller than 8.3 W/(mK). Inthe current embodiment, the thermal conductivity of the heat storagelayer 245 is between 1.689 and 8.203 W/(mK).

The second reflection layer 244 includes a second heat reflectionsurface 244 a which is made of metal, and faces the heat storage layer245 and the chamber 16. The second heat reflection surface 244 a couldreflect radiation heat back to the chamber 16, and thereby to stop 70%of the heat from dissipating out and could block heat convection aswell. When heat storage layer 245 is thermally saturated, the heatdissipates from the heat storage layer 245 would transfer back to thechamber 16 through the heat conduction layer 246, and thereby to provideheat insulation effect for the chamber 16. The thermal conductivity ofthe second reflection layer 244 is preferably between 0.62 and 0.72W/(mK). In the current embodiment, the thermal conductivity of thesecond reflection layer 244 is 0.67 W/(mK).

In addition, the heat conducted from the second reflection layer 244would be retained in the thermal insulation layer 243. The thermalconductivity of the thermal insulation layer 243 is equal to or smallerthan that of the heat storage layer 245. Preferably, the thermalconductivity of the thermal insulation layer 243 is lower than that ofthe heat storage layer 245. The barrier layer 242 is adapted to insulatethe heat convecting from the thermal insulation layer 243 so as tobarrier the convection heat and reduce the heat dissipation from thermalinsulation layer 243. The thermal conductivity of the barrier layer 242is greater than that of the thermal insulation layer 243 and smallerthan that of the heat storage layer 245. The first reflection layer 241includes a first heat reflection surface 241 a which is made of metal,and faces the thermal insulation layer 243 and the chamber 16. The firstheat reflection surface 244 a could reflect the heat radiated from thethermal insulation layer 243 back to the chamber 16. Preferably, theheat conductivity of the thermal insulation layer 243 is equal to orsmaller than 0.2 W/(mK). In the current embodiment, the heatconductivity of the thermal insulation layer 243 is between 0.04 and0.16 W/(mK). Preferably, the thermal conductivity of the barrier layeris between 0.4 and 0.6 W/(mK). In the current embodiment, the thermalconductivity of the barrier layer 243 is between 0.483 and 0.551 W/(mK).

A cladding layer 26 could be further disposed on the thermal insulationstructure 24, wherein the cladding layer covers the thermal insulationstructure 24 and the heat storage member 22, whereby to fix the thermalinsulation structure 24 and the heat storage member 22. However, thecladding layer 26 also could be omitted.

In the current embodiment, the first reflection layer 241 and the secondreflection layer 244 could be made of aluminum foil, which not onlycould reflect the radiation heat but also could effectively block theheat source, and further could provide water resistance and moistureresistance. The barrier layer 242 could include refractory material,such as lime. The thermal insulation layer 243 includes organic fibermaterial (e.g. ceramic fiber, glass fiber, rock wool, etc.) which isfilled with air, thereby forming the thermal insulation layer 243 with athermal conductivity similar to air so as to insulate heat. The heatstorage layer 245 could be formed by mixing materials of clay, stonematerial particles or powder, refractory material, cement, etc. The heatconduction layer 246 could be formed by mixing materials of siliconcarbide, magnesium oxide, refractory material, cement, etc.

In practice, except the thermal insulation structure having amulti-layer arrangement as described above, the thermal insulationstructure 24 also could have, but is not limited to, other types ofarrangement methods which would be illustrated below:

Type (1): at least including the heat conduction layer 246, the heatstorage layer 245, and the second reflection layer 244, wherein the heatconduction layer 246 contacts the chamber 16, and the heat storage layer245 is disposed between the second reflection layer 244 and the heatconduction layer 246;

Type (2): including the arrangement as mentioned in type (1), andfurther including the first reflection layer 241 and the thermalinsulation layer 243 on the second reflection layer 244; alternatively,further including the barrier layer 242 in addition to the firstreflection layer 241 and the thermal insulation layer 243, wherein thebarrier layer 242 is disposed between the thermal insulation layer 243and the first reflection layer 241;

Type (3): at least including the first reflection layer 241 and thethermal insulation layer 243, wherein the thermal insulation layer 243is disposed between the first reflection layer 241 and the chamber 16;

Type (4): in addition to the first reflection layer 241 and the thermalinsulation layer 243, further including the barrier layer 242, whereinthe barrier layer 242 is disposed between the thermal insulation layer243 and the first reflection layer 241;

Type (5): in addition to the first reflection layer 241 and the thermalinsulation layer 243, further including the heat storage layer 245,wherein the heat storage layer 245 is disposed between the thermalinsulation layer 243 and the chamber 16;

Type (6): including the arrangement as mentioned in type (5), andfurther including the second reflection layer 244, wherein the secondreflection layer 244 is disposed between the thermal insulation layer243 and the heat storage layer 245; alternatively, further including theheat conduction layer 246 in addition to the second reflection layer244, wherein the heat conduction layer 246 is disposed between the heatstorage layer 245 and the chamber 16, and contacts the chamber 16; and

Type (7): including the arrangement as mentioned in type (5), furtherincluding the heat conduction layer 246, wherein the heat conductionlayer 246 contacts the chamber 16, and the heat storage layer 245 isdisposed between the heat conduction layer 246 and the thermalinsulation layer 243.

In the current embodiment, the thermal insulation structure 24 isutilized in a heater which is the kiln 100 as an example, but it is notlimited thereto. The heat insulation structure also could be applied tochambers of other types of heaters, such as an oven, a baking apparatus,a heating apparatus, a thermal insulation apparatus, etc. A heatinsulation effect could be further achieved if the housing 36 isdisposed on the exterior of the insulation structure 24, and an air gapis formed therebetween as described in the current embodiment.

The stove 10 is disposed on a stage 30. In more details, the stove 10 ismounted on the stage 30 via the base 28, which at least includes acarrier plate 282 and a thermal insulation plate 284. In the currentembodiment, the base 28 includes two carrier plates 282 which face thecavity 12 and are adapted for placing food ingredients. The thermalinsulation plate 284 is disposed under the carrier plate 282 and acrossa plurality of frames of the stage 30. In practice, the carrier plate282 could be rock board as an example, and the thermal insulation platescould be rock wool as an example. An air isolation is disposed betweenthe stage 30 and the base 28 for heat insulation. A gas regulation valveis disposed in the stage 30 (not shown), wherein the gas regulationvalve includes a knob 32 disposed at a front side of the stage 30 for auser to adjust a flow rate of gas manually. An ignition switch 34 isfurther disposed at the front side of the stage 30.

The housing 36 is joined to the stage 30 and surrounds the stove 10,wherein an isolation space S2 is formed between the housing 36 and thestove 10. The housing 36 is made of metal such as stainless steel andincludes a front plate 362, a rear plate 364, and a cover 366. The frontplate 362 is joined to the stage 30 and disposed at a front side of theentry 14 of the stove 10; the front plate 362 includes a feeding opening362 a which communicates with the entry 14 and the exhaust channel Eformed by the guide plate 182 and the exhaust pipe 20. The front plate362 and the stove 10 are spaced apart with a distance D1. The rear plate364 is joined to the stage 30 and is disposed at a rear side of thestove 10. The rear plate 364 and the stove 10 are spaced apart with adistance D2. The cover 366 includes a front edge 366 a and a rear edge366 b which are respectively joined to the front plate 362 and the rearplate 364. A through hole 366 c is formed on the cover 366 above thefront section 122 of the cavity 12, wherein the through hole 366 c isadapted for penetration of the exhaust pipe 20. The cover 366 and thestove 10 are spaced apart with a distance D3. The isolation space S2consists of the distance D1, D2 and D3 which are respectively formedbetween the stove 10 and the front plate 362, the rear plate 364, andthe cover 366, and the isolation space S2 is adapted to insulate heatand avoid heat dissipating from the stove 10 to the housing 36 directlywhereby, in designing a compact kiln, the metallic chamber could providea sufficient support to sustain the thermal insulation structure, whichcould effectively improve the drawback of being difficult to be scaleddown in size corresponding to conventional kilns which are formed bystacking thick stone material. In addition, a flameproof layer 368 couldbe further disposed on an interior surface of the cover 366 of the cover366. The flameproof layer 368 is formed by a flameproof coating andadapted to reduce an amount of residual heat dissipated from the stove10 to the exterior of the cover 366 so as to avoid an over-hightemperature on the exterior surface of the cover 366. In the compactsize design, the flameproof layer 368 also could prevent the user frombeing burned by touching the cover 366. Furthermore, the flameprooflayer 368 also could be disposed on interior surfaces of the front plate362 and the rear plate 364, which could reduce the amount of residualheat dissipated from the stove to the housing 36 as well.

The door 38 is adapted to cover at least one portion of the entry 14.The door 38 includes a main plate 382, at least one shield 384, and ablocking plate 386, wherein the main plate 382 is detachably joined tothe stove 10 at the entrnce 14; the main plate 382 includes a pluralityof first vents 382 a and a plurality of second vents 382 b; theplurality of first vents 382 a are laterally arranged at the bottom ofthe main plate 382; the plurality of second vents 382 a are divided intotwo groups, and each of the two groups is disposed above the pluralityof first vents 382 a; the second vents 382 b of each group are arrangedin a circular shape. In the current embodiment, the door 38 includes twoshields 384, each of which is movably disposed on an exterior surface ofthe main plate 382 corresponding to each group of the second vents 382b. Each of the shields 384 includes a plurality of adjusting holes 384a. By turning the shields 384 to close the plurality of second vents 382b or partially shield the plurality of second vents 382 b, an air flowpassing through the plurality of second vents 382 b could be adjustedvia the adjusting holes 384 a. The blocking plate 386 is joined to aninner edge of the main plate 382, wherein the blocking plate 386 wouldclose the air outlet 164 a when the door 38 is at the entry 14. Whereby,the exhaust channel E formed by the air guide structure 18 and theexhaust pipe 20 would be isolated from the interior of the cavity 12.

The combustion device 40 is disposed within the cavity 12 at the rearsection 124 and includes at least one burner 42, a supporting assembly46, and an infrared ray generation assembly 54. In the currentembodiment, the combustion device 40 includes a plurality of burners 42,wherein the plurality of burners 42 jointly communicate with a flowdivider 44 via a plurality of terminals thereof, and then communicatewith a gas regulation valve disposed in the stage 30 through the flowdivider 44. A flame outlet 422 is disposed at another terminal of eachof the burners 42, and the burners 42 are adapted to burn gas togenerate flames through the flame outlets 422. An ignition assembly 56is disposed beside the burners 42, wherein the ignition assembly 56 isconnected to the ignition switch 34 and adapted for igniting gassupplied from the flame outlet 422; the ignition assembly 56 includes anignitor and a pilot pipeline. An axis i which passes through acorresponding center of each flame outlet 422 is extended along alongitudinal direction of each of the burners 42.

The supporting assembly 46 includes a cover plate 48 which issubstantially a bowl shape and disposed above the burners 42. In avertical direction, the cover plate 48 is located at a position with aheight greater than a half of the distance L between the top and thebottom of the middle section of the cavity 12 (as shown in FIG. 5). Thecover plate 48 includes at least one hollow area. In the currentembodiment, there are a plurality of hollow areas, including an opening482 and a plurality of holes 484, wherein the opening 482 iscorresponding to the flame outlet 422 of each of the burners 42. Theinfrared ray generation assembly 54 is disposed in the supportingassembly 46, and the cover plate 48 is disposed between the infrared raygeneration assembly 45 and the burners 42. In the current embodiment,the infrared ray generation assembly 54 is located above the cover plate48, such that the flames generated by the burners would pass through theopening 482 to apply on the infrared ray generation assembly 54, whichmakes the infrared ray generation assembly 54 generate infrared ray. Theinfrared ray generation assembly 54 includes an emission surface 542 ato emit infrared ray which faces the cover plate 48 and is correspondingto the opening 482 and the holes 484, thereby enabling the generatedinfrared ray to pass through the opening 482 and the holes 484. Inpractice, the emission surface 542 a is at least corresponding to theholes 484. An angle is formed between the emission surface 542 a and theaxis i, wherein the angle is between 100 and 135 degrees. In addition,another function of the cover plate 48 is to maintain a temperature ofthe infrared ray generation assembly 54 so as to reduce heat dissipationof the infrared ray generation assembly 54.

In the current embodiment, the supporting assembly 46 further includes asupporting plate 50 and another cover plate 52. Wherein, the supportingplate 50 includes a first part 502 and a second part 504; the secondpart 504 is located above the first part 502, and an obtuse angle isformed between the first part 502 and the second part 504; the firstpart 502 and the inner wall surface 124 a of the rear section 124 arespaced apart with a gap a1, while the second part 504 and the top wallsurface of the rear section 124 are spaced apart with a gap a2. Theburners 42 are mounted to the first part 502, and said another coverplate 52 is mounted to second part 504 and joined to the cover plate 48,whereby the two cover plates 48, 52 jointly form a containing space S3.The infrared ray generation assembly 54 is disposed in the containingspace S3. Said another cover plate 52 also includes a plurality of holes522, and also could maintain the temperature of the infrared raygeneration assembly 54 so as to reduce heat dissipation of the infraredray generation assembly 54.

The infrared ray generation assembly 54 includes an infrared raygeneration mesh 542 and a reflection plate 544. The infrared raygeneration mesh 542 includes two surfaces which are opposite to eachother, wherein one of the two surfaces is the emission surface 542 a,while the other surface is the emission surface 542 b which faces areflection surface 544 a of the reflection plate 544. The reflectionsurface 544 a is an arc surface which is concaved toward a directionaway from the infrared ray generation mesh 542, whereby the infrared rayemitted by the other emission surface 542 b could be centralized andreflected downwardly. The cover plate 48 includes an exterior surfacehaving an arc shape and is protruded outwardly toward a direction awayfrom the infrared ray mesh 542 of the infrared ray generation assembly54. The cover plate 48 also could generate infrared ray by heating,while the arc-shape exterior surface thereof could increase a rangecovered by the infrared ray. In the current embodiment, the infrared raymesh 542 includes a plurality of grids, each of which includes a sizesmaller than that of each of the holes 484, 522 of the cover plates 48,52. The flame outlets 422 of the burners 42 are corresponding todifferent portions of the infrared ray generation mesh 542 respectively.

The infrared ray generation mesh 542 could be an alloy mesh, such asheat-resistant steel (e.g. FCHW2) mesh, iron-chromium-aluminum alloymesh, iron-nickel-aluminum alloy mesh, etc. The two cover plates 48, 52could be made of different stainless steel material. The reflectionplate 544 could be made of metal alloys which reflect infrared ray. Inpractice, the reflection plate 544 also could be omitted.

The infrared ray generation assembly 54 and the cover plate 48constitute a heating device of the heat source and are adapted togenerate heat for heating the cavity 12, which could heat the foodingredients from top down so as to make surfaces of the food ingredientsto be heated uniformly.

With the aforementioned structure, a heating method for the kiln 100according to the present invention includes the following steps.

First, the user adjusts the knob 32 of the gas regulation valve and theignition switch 34 to control the burners 42 to generate flames. Asillustrated in FIG. 7 to FIG. 10, after generating the flames, theinfrared ray generation assembly 54 is heated by the flames to generateinfrared ray. In the current embodiment, the flames apply to theinfrared ray generation mesh 542, which makes the two emission surfaces542 a, 542 b to emit infrared ray. Wherein, the infrared ray emitted bythe emission surface 542 a, which is close to the cover plate 48,irradiates on the carrier plate 282 through the holes 484 of the coverplate 48, thereby providing a larger heating area. Meanwhile, theinfrared ray emitted by the emission surface 542 b which is close to thereflection plate 544 is reflected to the infrared ray generation mesh542 by the reflection surface 544 a of the reflection plate 544, andirradiates on the carrier plate 282 through the grids of the infraredray generation mesh 542, and the holes 484 of the cover plate 48 so asto increase an intensity of the infrared ray irradiated on the carrierplate 282. Since the angle formed between the axis i of the burners andthe emission surfaces 542 a, 542 b of the infrared ray generation mesh542 is between 100 and 135 degrees, the flames could be uniformly actedon the emission surfaces 542 a, 542 b of the infrared ray generationmesh 542, which achieves an optimal performance for the infrared rayemission. The flames generated by the burners 42 also apply on the coverplate 48 to make the cover plate 48 to generate infrared ray, andthereby to increase the intensity of the infrared ray irradiated on thecarrier plate 282.

The temperature of the infrared ray generation assembly 54 is maintainedto be between 900 and 100° C., and the infrared ray generation assembly54 is blocked by the cover plate 48, which enables the infrared rayhaving an optimum range of infrared ray wavelength to pass through theholes 484 of the cover plate 48. Preferably, a wavelength range isbetween 4 to 8 μm, which could provide a better transmission efficiencyfor the heated food ingredients on the carrier plate 282 so as to heatan interior of the food ingredients. A temperature on the exteriorsurface of the cover plate 48, i.e., the surface which faces toward adirection away from the infrared ray generation assembly 54, is between600 and 800° C.

The flames generated by the burners 42 penetrates upwardly through theholes 484, 522 of the two cover plates 48, 52 to form an open fire atthe top of the middle section 126. The open fire is adapted to heat thesurface of the food ingredients, such as scorching the surface of thefood ingredients to form golden color. Whereby, the combustion device 40could have a larger heating area so as to achieve a uniform heating andincrease a heating efficiency.

Since coke is formed on the infrared ray generation assembly 54 when gasburns, and an over-heated steam is generated from the steam formed byburning the gas, a reaction to generate water-gas which includeshydrogen and carbon monoxide would occur when the over-heated steampasses through the hot coke having a temperature between 900 and 1100°C. on the infrared ray generation assembly 54, which provides anauxiliary fuel to the gas burning.

For example, water-gas is generated when the steam passes thehigh-temperature coke according to equation 1:

C+H₂O→H₂₊CO−113.4KJ  (1)

Wherein, the generation heat equals to −113.4 KJ, which represents thatequation 1 is an endothermic reaction. However, the generated hydrogenand carbon monoxide would react with the steam formed in the combustionaccording to equation 2, which is an exothermic reaction.

CO+H₂O→H₂+CO₂+42.71KJ; H2+½O₂H₂O+237.4KJ  (2)

A total generation heat of equation 2 equals to 280.11 KJ. An overallreaction heat of equation 1 and equation 2, which subtracts 113.4 KJfrom 280.11 KJ, would be 166.71 KJ. It could be understood that thegeneration of the water-gas when the over-heated steam passes throughthe coke on the infrared ray generation assembly 54 could increase aheating efficiency, whereby a consumption of gas could be reduced. Theadvantage of placing the infrared ray generation assembly 54 between thetwo cover plates 48, 52 is that the temperature of the infrared raygeneration assembly 54 could be kept between 900 and 1000° C. which isnecessary for generating the water-gas under a limited amount of gasconsumption by utilizing the cover plates 48, 52 to maintain thetemperature of the infrared ray generation assembly 54. Meanwhile, thecover plates 48, 52 are concaved toward a direction away from theinfrared ray generation assembly 54, which enables part of the heat tobe concentrated and reflected back to the infrared ray generationassembly 54, thereby providing a better performance in maintaining thetemperature. In contrast, simply utilizing the cover plate 48 also couldmaintain the temperature of the infrared ray generation assembly 54between 900 and 1000° C., but the gas consumption thereof would behigher than that of the examples of utilizing the two cover plates 48,52.

A temperature of the overheated steam is about 300° C. and higher,wherein water molecules would become smaller water vapor which couldpenetrate food and dissolve fat at high temperature to increase aheating efficiency of cooking food ingredients, whereby the over-heatedsteam also could be adapted to heat food ingredients. Moreover, thewater vapor generated from the food ingredients also would be heated toform over-heated vapor so as to further increase the heating efficiency.

The burners 40 creates a high-temperature zone at a higher position tomake the hot air flow formed by combustion, i.e., the hot air flowformed by the heat generated from the heating assembly of the heatsource, be guided downwardly by the wall surface of the top of the frontsection 122 of the cavity 12, which facilitates the hot air flowing backto the burners 42 and reduces heat dissipation. Meanwhile, external airwould be drawn in from the entry 14 as combustion-supporting airtogether with the flowing-back of the hot air flow. By mixing theexternal air with the hot air flow which flows back, a temperature ofthe air flowing back to the burners 42 could be increased to avoid coldair directly flowing back to the burners 42, whereby heat dissipationcould be reduced so as to increase heat efficiency. Moreover, thethermal insulation structure 24 covers the chamber 16, which couldmaintain the temperature inside of the cavity 12, prevent heatdissipating from the combustion device 40 through the chamber 16, andthereby to keep the temperature of the infrared ray assembly 54 between900 and 1100° C. and reduce the gas consumption. The heat storage member22 would absorb part of the heat from the top of the front section 122of the cavity 12, which makes the temperature at the top of the frontsection 122 be lower than the temperature at the top of the middlesection 126 so as to drive the hot air to flow downwardly whereby, theflowing back of the hot air could be increased, and the heating effectwould be improved. Besides, it is also favorable to keep the temperatureof the infrared ray generation assembly 54 between 900 and 1100° C. andreduce the gas consumption.

With the heating method as described above, the food ingredients in thechamber could be heated sufficiently, and the gas consumption could bereduced as well.

Furthermore, a retained air flow could be generated in the gap a1 andthe gap a2, which are respectively formed between the first part 502 ofthe supporting plate 50 and the inner wall surface 124 a at the rearsection 124 of the cavity 12, and between the second part 504 of thesupporting plate 50 and the top wall surface at the rear section 124 ofthe cavity 12, to pull the hot air flow, which flows back, to moveupwardly again, and thereby to make a circulation effect of the hot airflow in the cavity 12 become better.

In addition, redundant hot air flow would be exhausted from the outlet164 a to the outside through the air guide structure 18 and the exhaustpipe 20. During the exhaust process, cold air would be drawn in from theoutside via the feeding opening 362 a of the front plate 362 and theentry 14, and then be pulled up to the air guide structure 18 and theexhaust pipe 20 through the air outlet 164 a so as to lower atemperature of the front plate 362 and a temperature of the exhaust pipe20, thereby avoiding the user to be burned by the front plate 362 andthe exhaust pipe 20. Since the heat storage member 22 contacts the airguide structure 18, part of the heat of the heat storage member 22 wouldbe transferred to the air guide structure 18 to heat the exhaust channelE, which results in rising of steam as an upward pulling force to speedup an exhaust rate of the hot air flow, and thereby to increase theexhaust efficiency and improve the circulation effect of the hot airflow in the cavity. The guide plate 182 which tilts upwardly is alsofavorable to increase air guide performance such that the exhaustefficiency could be further improved. Meanwhile, the increase in theexhaust rate of the hot air flow also would increase the speed of coldair drawing into the air guide structure 18, which could make thetemperature of the front plate 362 and the exhaust pipe 20 become lower.The exhaust pipe 20 is located at the top of the front section 122 ofthe cavity 12, which could make the exhaust path be shorter, whereby theair flow could be exhausted out faster.

A combustion device 60 of a second embodiment according to the presentinvention is illustrated in FIG. 11 and FIG. 12. The combustion device60 of the second embodiment includes a basic structure similar to thecombustion device 40 of the first embodiment, and further includes asteam generation assembly 62, which is adapted to generate steam to beused as an over-heated steam for combustion. The steam generationassembly 62 includes a steam source which is a water tank 64 as anexample, a first pipe 66, and a second pipe 68. Wherein, the water tank64 is disposed at one side of the burners 42. In more details, the watertank 64 is mounted on the first part 502 of the supporting plate 50, andis located between the first part 502 and the burners 42. The water tank64 includes a water inlet 642 for filling water. The first pipe 66 isconnected to a top of the water tank 64, and two terminals of the firstpipe 66 communicate with an interior of the water tank 64. A section 662of the first pipe 66 includes a plurality of spraying holes 662 a. Inpractice, there could be only one spraying hole 662 a, and the section662 is located between the flame outlet 422 of the burners 42 and thereflection surface 542 a of the infrared ray generation assembly 54. Twoterminals of the second pipe 68 are respectively connected to two sidesof the water tank 64 and communicate with the interior of the water tank64. The second pipe 68 surrounds the burners 42, and a section 682 ofthe second pipe 68 is located below the exterior surface of the coverplate 48. The burners 42 are located between the section 682 of thesecond pipe 68 and the water tank 64. The section 682 includes aplurality of spraying holes 682 a which face toward the front section122 of the cavity 12. In practice, there could be only one spraying hole682 a.

After heating of the water contained in the water tank 64 of the steamgeneration assembly 62, the water becomes steam which would spray outfrom the spraying holes 662 a of the first pipe 66, wherein the steamcould be either guided to the infrared ray generation mesh 542 by thefirst pipe 66 to be used as the over-heated steam for forming thewater-gas, or be used as the over-heated steam for heating the foodingredients. The steam which sprays out from the spraying holes 682 a ofthe second pipe 68 is mainly used as the over-heated steam for heatingthe food ingredients, however, also could be used as the over-heatedsteam for forming the water-gas.

With the steam generated from the steam generation assembly 62 as thesource of the over-heated steam, the heating efficiency could beimproved efficiently. In practice, the steam generation assembly 62could only include the first pipe 66 or the second pipe 68. On the otherhand, the steam source also could be disposed outside of the cavity 12,and the first pipe 66 and the second pipe 68 could be directly connectedto the steam source.

As illustrated in FIG. 13 and FIG. 14, a kiln 300 of a third embodimentaccording to the present invention includes a structure which is similarto that of the first embodiment, wherein the kiln 300 of the thirdembodiment is different from that of the first embodiment in that in thecurrent embodiment, a first inclined plate 704, and a second inclinedplate 706 of a chamber 70 are respectively joined to a main body 702 ofthe chamber 70 with edges of the main body 702, the first inclined plate704, and the second inclined plate 706, which are to be joined, beingbent in advance, which forms a plurality of ridges 70 a. The ridges 70 acould reinforce the strength of the chamber 70 and avoid the heatstorage member 22 or the thermal insulation structure 24 from slidingdown effectively. For example, part of the heat storage member 22 whichis outside of the space S1 is surrounded by the plurality of ridges 70 aat the periphery of the first inclined plate 704, thereby avoiding theheat storage member 22 from sliding down from the first inclined plate704. Meanwhile, the ridges 70 a at other positions of the chamber 70could prevent the thermal insulation structure 24 from sliding down,which reinforces the joined strength of the chamber 70 and the thermalinsulation structure 24.

In the current embodiment, an exhaust pipe 72 includes an outer pipe 722and an inner pipe 724, wherein one end of the outer pipe 722 isconnected to the housing 36, and the outer pipe 722 is adapted tocommunicate the isolation space S2 inside of the housing 36 with anoutside of the cover 366; the inner pipe 724 penetrates through thethrough hole 366 c, and the inner pipe 366 is adapted to communicate theair guide structure 18 with the outside of the cover 18, whereby theredundant hot air in the isolation space S2 could be exhausted outthrough the outer pipe 722 so as to reduce heat dissipation from theisolation space S2 to the housing 36 and lower the temperature of thefront plate 362. The configuration of the outer pipe 722 and the innerpipe 724 of the exhaust pipe according to the current embodiment alsocould be utilized in the first embodiment.

In addition, a carrier plate 74 of the current embodiment is a discshape and is rotatably disposed on the bottom of the chamber 70. In moredetails, a driving motor 78 is further disposed on a stage 76. Thedriving motor 78 is connected to the carrier plate 74 via a rotationmember 80 to drive the carrier plate 74 to rotate, whereby, the foodingredients disposed on the carrier plate 74 could be uniformly heated.The rotatable design of the carrier plate 74 of the current embodimentalso could be utilized in the first embodiment.

As illustrated in FIG. 15, a kiln 400 of a fourth embodiment accordingto the present invention includes a structure which is similar to thatof the first embodiment. The kiln 400 of the current embodiment isdifferent from that of the first embodiment in that the gas regulationvalve provided in the first embodiment is adapted for the user to adjustthe gas flow rate of the burners 42 manually, but a control system isprovided in the current embodiment to replace the manual adjustmentinstead. In the current embodiment, the control system of the kiln 400includes a thermometer 82, a flow rate regulation device 84, and acontrol device 86, wherein the flow rate regulation device 84 and thecontrol device 86 are disposed in the stage 30, which would be describedin detail as follows.

The thermometer 82 is disposed in the cavity 12 to detect thetemperature inside of the cavity 12. In the current embodiment, thethermometer 82 is located at the middle section 126 of the cavity 12.However, the thermometer 82 also could be disposed at the front section122 of the cavity 12.

The flow rate regulation device 84 communicates with at least one of theburners 42, and a flow rate regulation valve 844 is controlled to adjusta gas flow of the at least one burner 42. In the current embodiment, theflow rate regulation device 84 includes a channel valve 842 and a flowrate regulation valve 844, wherein one end of the channel valve 842 isconnected to the gas source; one end of the flow rate regulation valve844 is connected to the channel valve 842, and another end of the flowrate regulation valve 844 communicates with the burners 42. The channelvalve 842 could be controlled to close or open so as to shut or pass thegas. The flow rate regulation valve 844 could be controlled to regulatethe gas flow to be transported to the burners 42.

The control device 86 is electrically connected to the thermometer 82,and the channel valve 842 and the flow rate regulation valve 844 of theflow rate regulation device 84. The control device 86 is alsoelectrically connected to the ignition assembly 56, an input unit 88,and a display unit 90, wherein the input unit 88 is adapted for the userto input an ignition command, and a setting temperature; the displayunit 90 is adapted to display a message.

After inputting the ignition command via the input unit 88 by the user,the control device 86 would control the ignition assembly 56 to igniteand the channel valve 842 to open so as to ignite the gas of the burners42. Then, the control device would control the flow rate regulationvalve 844 of the flow rate regulation device 84 to adjust the outputtedgas flow based on the inputted setting temperature and the temperatureof the cavity which is detected by the thermometer 82, and thereby tomaintain the temperature inside of the cavity at a constant temperaturerange corresponding to the setting temperature. Whereby, an automatictemperature control could be realized.

In order to fulfill the object of infrared ray heating, the infrared raygeneration assembly 54 of the combustion device 40 would generateinfrared rays of a predetermined wavelength range which irradiate towardthe middle section 126 and the front section 122 of the cavity 12 whenthe gas flow output from the flow rate regulation device 84 is above apredetermined flow rate. The predetermined wavelength range is between 4and 9 μm. When the temperature detected by the thermometer 82 is betweenthe constant temperature range or higher than an upper limit of theconstant temperature range, the control device 86 would control the flowrate regulation valve 844 of the flow rate regulation device 84 to makethe gas flow output from the flow rate regulation valve 844 be equal toor higher than the predetermined flow rate, whereby, in addition to keepthe cavity 12 at a constant temperature, the infrared ray generationassembly 54 also could generate infrared ray for heating foodingredients. If a maximum gas flow rate is determined as the gas flowoutput from the regulation device 84 when the regulation device 84 isbeing controlled, the predetermined flow rate is preferably equal to orhigher than one-third of the maximum gas flow rate.

In the current embodiment, the kiln 400 further includes an infrared raydetector 92, a flame sensor 94, and a carbon monoxide detector 96 whichare electrically connected to the control device 86 respectively. Theinfrared ray detector 92 is disposed at the bottom of the middle section126 of the cavity 12, and adapted to detect the infrared ray emitted bythe combustion device 40. When the wavelength of the infrared raydetected by infrared ray detector 92 is between the predeterminedwavelength range, the control device 86 would control the display 90 todisplay a prompt message (e.g. a light signal or a text message) toremind the user that the infrared ray suitable for penetrating foodingredients is already generated by the combustion device 40. Of course,the infrared ray detector 92 also could be disposed at the front section122 of the cavity 12.

The flame detector 94 is disposed at the top of the middle section 126of the cavity, and is higher than the infrared ray generation assembly54. When a flame is detected by the flame detector 94, the controldevice 86 would control the display unit 90 to display a prompt messageto remind the user that an open fire is already generated and could beused to heat the food ingredients.

The carbon monoxide detector 96 is disposed in the exhaust channel E,and adapted to detect a concentration of carbon monoxide in the air flowpassing through the exhaust channel E. When the concentration of thecarbon monoxide detected by the carbon monoxide detector 96 is higherthan a predetermined value, the control device 86 would control thechannel valve 842 of the flow rate regulation device 84 to shun the gas.It is favorable to avoid the concentration of the carbon monoxidecontained in the exhausted gas from becoming too high to harm the humanbody.

As illustrated in FIG. 16, a kiln 500 of a fifth embodiment according tothe present invention includes a structure which is similar to that ofthe fourth embodiment. The kiln 500 of the fifth embodiment is differentfrom that of the fourth embodiment in that a flow rate regulation device98 of the current embodiment includes a plurality of gas switch valve982, which are electrically connected to a control device 99. Theplurality of gas switch valves 982 communicate with the burners 42respectively, and could be controlled by the control device 99 to closeor open respectively, and thereby to adjust the gas flow output to theburners 42. When all of the gas switch valves are open, a gas flowoutput to the burners 42 is a maximum gas flow rate; when only one ofthe gas switch valves 982 is turned on, the gas flow output from theflow rate regulation device 98 is the predetermined flow rate whichenables the combustion device 40 to generate the infrared ray of thepredetermined wavelength range. When the temperature detected by thethermometer 82 is between the constant temperature range or higher thanthe upper limit of the constant temperature range, the control device 99would control at least one of the gas switch valves 982 to open, wherebythe infrared ray generation assembly 54 could be maintained at thetemperature which enables the combustion device 40 to generate theinfrared ray of the predetermined wavelength range.

In the current embodiment, when the temperature detected by thethermometer 82 is between the constant temperature range or higher thanthe upper limit of the constant temperature range, the control device 99would control the gas switch valves 982 to be open by turns so as tomake the burners 42 generate flames sequentially. For example, if onlythe first gas switch valve 982 is turned on, the second gas switch valve982 would be turned on after a period of time and then the first gasswitch valve 982 would be turned off; the third gas switch valve 982would be turned on after another period of time, and the second gasswitch valve 982 would be turned off; thereafter, the first gas switchvalve 982 would be turned on again, and the third gas switch valve 982would be turned off. In this way, the burners 42 could generate flamesby turns to heat different portions of the infrared ray generationassembly 54, and thereby to avoid the flames from only applying on asingle position, which results in the infrared ray generation assembly54 to degrade and be damaged earlier. The control systems of the fourthand the fifth embodiments also could be utilized in the second and thethird embodiments.

As mentioned above, with the structural design of the combustion deviceand the stove, the kiln of the present invention is favorable toincrease the heating efficiency and shorten a cooking time of the foodingredients. In addition, the combustion device and the thermalinsulation structure of the present invention are not limited to beapplied to kilns, and could be utilized in other heating apparatus. Theaforementioned combustion devices are not limitations to the kilns ofthe first, the second, and the third embodiments, however, the kilnsalso could include firewood, fire rows disposed in the cavity, or anelectrothermic heat source, and preferably the kilns could include aheat source which is capable of generating infrared ray.

It must be pointed out that the embodiments described above are onlysome embodiments of the present invention. All equivalent structureswhich employ the concepts disclosed in this specification and theappended claims should fall within the scope of the present invention.

What is claimed is:
 1. A thermal insulation structure for a heatingdevice, being disposed at an exterior of a chamber of the heatingdevice, wherein a heat source is disposed within the chamber,comprising: a heat conduction layer disposed on the exterior of thechamber; a heat storage layer disposed on the heat conduction layer andcontacts the heat conduction layer, wherein the heat conduction layer isadapted to conduct heat from the chamber to the heat storage layer; anda reflection layer disposed on the heat storage layer and including aheat reflection surface which faces the heat storage layer.
 2. Thethermal insulation structure of claim 1, wherein a thermal conductivityof the heat conduction layer is greater than that of the heat storagelayer.
 3. The thermal insulation structure of claim 2, wherein thethermal conductivity of the heat conduction layer is equal to or greaterthan four times of that of the heat storage layer.
 4. The thermalinsulation structure of claim 3, wherein the thermal conductivity of theheat conduction layer is equal to or greater than 35 W/(mK).
 5. Thethermal insulation structure of claim 4, wherein the thermalconductivity of the heat conduction layer is equal to or greater than 40W/(mK).
 6. The thermal insulation structure of claim 3, wherein thethermal conductivity of the heat storage layer is equal to or smallerthan 8.5 W/(mK).
 7. The thermal insulation structure of claim 6, whereinthe thermal conductivity of the heat storage layer is equal to orsmaller than 8.3 W/(mK).
 8. The thermal insulation structure of claim 1,further comprising another reflection layer and a thermal insulationlayer, wherein the thermal insulation layer is disposed between thereflection layer and said another reflection layer, and said anotherreflection layer includes a heat reflection surface which faces thethermal insulation layer; a thermal conductivity of the thermalinsulation layer is equal to or smaller than that of the heat storagelayer.
 9. The thermal insulation structure of claim 8, wherein thethermal conductivity of the thermal insulation layer is equal to orsmaller than 0.2 W/(mK).
 10. The thermal insulation structure of claim9, wherein the thermal insulation layer includes fiber material.
 11. Thethermal insulation structure of claim 8, further comprising a barrierlayer disposed between the thermal insulation layer and said reflectionlayer; the barrier layer is adapted to barrier a convection heat. 12.The thermal insulation structure of claim 11, wherein a thermalconductivity of the barrier layer is greater than that of the thermalinsulation layer, and smaller than that of the heat storage layer. 13.The thermal insulation structure of claim 12, wherein the thermalconductivity of the barrier layer is between 0.4˜0.6 W/(mK).